Improvement in alr-endlnes



J. ERIGSSON.

AIR ENGINE.

PATENTED JULY 31, 1855.

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UNITED STATES PATENT QFFICF.

JOHN ERIOSSON, OF .NE YORK, N. Y.

IMPROVEMENT lN. AIR-ENGINES.

Specification forming part of Lettcrs Patent No. 13,348, dated July 31,1955.

To an whom it may concern.-

' Be it known that I, John ERICSSON, of the eity,couuty, and State ofNew York, have invented an Improved Air-Engine for Producing MotivePower by Heated Air, of which the followingis a full, clear, and exactdescription, reference being had to the accompanying part of thisspecification,

drawings, making in which- Figure l is a plan, with the two cylinders,

the. pistons,

of the cylinders, the piston,and the air-heating apparatus in section toexhibit the internal arrangement.

.The same letters indicate like partsin the The heated air, after havingperformed its olfice in the working-cylinder of mypresent improvedair-engine, may be made to circulate through a vessel containing aseries of tubes, precisely as in my former engine referred to, and thecurrent of heated air in passing through saidvessel (called theregenerator) may be met by a current of cold air circulating in anopposite direction through the series of tubes on its way to theworking-cylinder, by which a transfer of caloric is effected between thetwo currents of air passing off .-from and entering the-working-cylinder,pre-

cisely as in my said former engine, and the current of cold air on itsway'to the workingcylinder, alter having been thus partially heated'bythe described process of transferring the caloric, isafterward made topass through a series of tubes or other vessels exas in my said formerengine, or in any other suitable man ner; but although the means adoptedfor heatingand for transferring the caloric from the escaping to theentering air is quite similar to that invented by me in the year 1833,yet the mechanism or engine which I have now and the air-heatingapparatus in; section; and Fig. 2 is a side elevation,with onedescriptions and invented for rendering the heating of the air, asdescribed, subservient in producing motive power dili'ers altogetherfrom anything hitherto known. Before, however, describing my invention Ideem it proper first to notice, in order that its nature may becorrectly understood, that in all air-engines on what is called thedifferential principle (my improved airengine for which .I obtainedpatents in 1851, for instance) the motive energy depends solely on thedifference of areas of the working and "supply pistons. Experience hasin the meantime demonstrated that in order to-obtain a sufiicient supplyof air without resorting to a dangerously high temperature thesupplypu'mp must be of such large capacity that the difierential(active) area becomes too small. Unless, therefore, future experienceshould suggest so'meimprovement, the power of such engines will alwaysbe, found insntficicnt for practical purposes.-

I will now proceed to dcscribcthe principal feature of my invention,which consists in charging the regenerator and heater-,or either,

with fresh compressed atmosphericair at each, stroke of the enginewithout the employment of asupply-pump by the peculiar combinedmovements of two pistons within the workingcylinder, the introduction offresh air and its transfer to the regenerator or heater in a compressedstate being efi'ected under a state of equilibrium .of pressure, so thatthe supply- .piston becomes entirely relieved .from resistance duringthe process of charging the regenerator or heater, while at the sametime one of thesepistons performs'the office of working-piston, exertingfull force on the en-' gine without suffering retardation by anyunbalanced pressure against the supply-piston.

My said engine is single-acting, and I connect two of them by acrank-shaft, placing the two cranks at an angle of one hundred andeighty degrees, so that while the piston of one engine is beingimpelledbythe tension of heated air the piston ot' the-other shall be making itsreturnstroke, and vice versa, and as the two engines are identical inconstruction the description of one of them will answer for the two.'lhemanner of connecting thetwo and the ellecls resulting therefrom willbe subsequently described.

The cylinder at is open at one-end and has a head, I), at the other,with a central aperture, 0, leadingto a valve-chest, d, with aninduction-port,-e, and an exhaust-porn)", fitted with valvesg and h. Thestem of-the valveg passes through the'hollow stem of the valve h, and

I these valves are to be operated by any known and suitable valve-geargiving the periods of movements such as will be presently described. Theexhaust-port leads by a pipe, 'i, to a chamber, j, surrounding a seriesof small tubes, k, constituting what has been termed the regenorator, sothat the air passing-from the cylinder to the escape-pipe lshallcirculate around and among the series of tubesfto impart its heat to thecold supply-air contained within the tubes, and the induction-portcommunicates with the tubesm of what is termed the heater. The series oftubes 70, constituting the regenerator, are suitably secured to a tube--sheet, n, at each end, and open into two chambers, o and pthe one, 0,communicating by a pipe,-q,witha port in the side of the cylinder,governed bya self-acting valve, 1", opening outward, and the other, 1),communicating with.

the heatertubes m, which are to be suitably coiled or otherwise arrangedto presenta large extent of surface "to. the action of the heat evolvedfrom the fire of a furnace, s, the series of tubes at being placed abovethe fire, so that the products of combustion in passing to the flue tshall circulate around and among them. The bottom plate of the flue t isa tube-sheet, to which are secured a series of flue-tubes, u, down whichthe products of combustion pass to a flue, w, below, leading to thechimney.

The flue-tubes u are inclosed ina chamber having an aperture, 1), nearthe bottom, to receive acurrent of air from the atmosphere, and anotheraperture, :0, near the top, through which the current of air passesafter circulating around and among the flue-tubes by which it IS heated,so that the products of combustion escape into thefat-mos'phereat-a verylow temperature, for it will be observed that the two currents'travelinopposite directions, the atmospheric current passing from the coldesttoward the hottestends of the flue-tubes gradually absorbing the heatfrom the products of combustion which are passing through-the tubes'inthe opposite direction.

From the passage as the partially-heatedair:

passes down a vertical flue or tube, y, two apertures, 2 and a, bothgoverned by dampers or registers, one leading below the grate in thefurnace to supply the fire when having .more "heat is required, andthe'other above the fire to admit-the air directly to the heater-tubes;

m when it becomes necessary to moderate the heat of the tubes. By thisarrangement a great saving of fuel is efiected and the attendant cancontrol and regulate the heat of the heatertubeswith perfect ease.

To'the cylinder are fitted two pistons, Hand 0. The one, b, is nearestthe open end of the cylinder and called the working-piston, and isprovided with a s'eli'ractingvalve,

iug inward, and the other, e, termed the supply-piston, is placedbetween the workingd, openpiston-and tlie head of the cylinder.

supply-piston, are

The rod f of the supply-piston passes through a stufifingbox, e, in theworking-piston. -This piston-rod embraces theend of an arm, g,'thatvibrates on a fulcrum-pin, h, and the arm carries two rollers, 1', andj-one on each side of the fulcrum-pin h-which rollers, for the purposeof governing the motions of the alternately acted 'upon by two earns, 70and-l, on the crankshaft m, the earn it acting on the roller and theother, I, on the rollerj. Y v

- In Fig.1 the arm and thetwo cams are concealed on one of the engines,but representedon the other, and in Fig. 2 the'arm. and. its rollers arerepresented infthe two opposite ex treme positions. The cam k operateson the roller 1; tocarry the supply-piston inwardtoward the head of thecylinder, and the other cam, Z, controls or governs'its motion in theopposite direction when impelled during a part of its movementbytheheat'ed air.

The workingpiston is provided with two wrist-pins, m m'-one on each sideof the stuff-" ing box ewhich are taken hold of by two connecting-rods,n n, connected with a vibrating arm, 0, on a rock-shaft, p, which isprovided. with another arm, q, at the angle indicated on the drawings,and the arm q'isin turn connected by a rod,'r, with the crank s on thecrank-- shaft m, before named.

The required motions are'to beiinparted to the induction and eductionvalves by suitable valve-gear taken fore stated, gines are connectedwith 'one-and the same orank-shaft-,with the 'crankson opposite sides,as the pistons of one are impelled. by theheated air anypowerrequired,tocausathe pistons of the other engine to return wiithederived from i this so'urc'e'if the momentuinjof'the moving parts benotsuifi'cientfor thisp'urposer Having describedthe construction o'fon'e ofthe engines with its regeneratorand heater,

from the crank-shaft, as beand stated thatthe two single acting enginesare alike in every respect, as-indiieated bycorand having respondingletters of reference, also described inwhat manner thettw'o areconnected, I will now'describe the .mode of'op e'ration, assuming thatthe furnaces oi. the heatershave'been properly fired up.

Byjmeans of a hand air-pumpappli'ed to the chamber 1) at one end of theregenerator,o r any other part of the regenerator or heater-tubes, I

" 'introdnce a supply of atmospheric air at about the pressure of theatmospherefand then the engine is in a conditionto begin its operations.

The cranks should'be turned over or beyond. the dead-point, asusual insteam -englnes. Starting with the pistons of one engine in the positionrepresented in Fig. 2, at the extremityof their outward stroke, as thecrank s,

moving in the direction indicated bythe arrow, is making that part ofits circuit near the outer dead-point, and therefore imparting butlittle moti'hn to'the working-piston b, the supply-piston c iscarriedfrom the'workingpiston and toward the head. of the cylinder with and asthe two single-acting enand nearthe end gradually a rapid motion by theaction of the cam k on being formed as represented, that the piston maybe gradually started, rapidly-accelerated, arrested, and there retainedin a state of rest as the extremity of the cam passes the roller. Duringthis in ward motion of the supply-piston theworki-ngpiston makes but asmall portion of its inward stroke, and therefore the valve df in theworking-pist0n will be opened by the pressure of the atmosphere topermit cold air to enter and fillv that part of the cylinder between thetwo pistons.- So soon as the supply-piston stops the exhaust-port closesand the continued inward motion of the working-piston begins to compressthe cold air thus supplied, which of course closes the self actingvalved, through which the supply was admitted by atmospheric pressure. Thissupplied cold air continues to be compressed by the workingpiston untilthe end of the time being from the other'engine it isimportant toobserve the condition of the connec tions. l

At the time the supply-piston of one engine is started and the air isentering by atmospheric pressure, and when the arm 0 on the rock-shaftp,with which the working-piston is connected by the rod n, is at itsgreatest leverage the corresponding arm of the rock-- shaft'of theopposite engine is atits shortest leverage; but as moved inward, and thesuppl y-air,'. by reason of being gradually compressed, increases theresistance,'the arm 0 gradually shortens in leverage, and the same armof the opposite engine gradually and in nearly the same ratio increasesin leverage, on the principle of the bent lever, thus applying the powerrequired to compress the supply-air to the best advantage. It should beborne in mind, however, that the power thus applied to compress thesupply-air is not actually expended, but merely borrowed, for it is somuch added to the elastic force of the air by which, when heated,theengine is impelled.

Just before the supply-piston begins the inward stroke just described,the eduction'valve g is opened, the induction-valveh having beenpreviously closed, so that the charge of heated air by which theprevious stroke of the engine was effected ispermitted to escape freelyinto the atmosphere, so that the power required to move thesupply-piston inward is very slight,

the air escaping freely to the atmosphere on one side and entering byatmospheric pressure on the other through the valve d,- but as theheated air exhausts or escapes from the cylinder it passes around andamong the series ofsmall tubes it of the regenerator. thus imparting itsheat througlpthe metal of the tubes to the cold air contained insideofthe tubes,which air is thus partially heated preparatory to be ingfinally heated in passing through the heater-tubes. In this way much ofthe-heat its inward stroke, and as the power' for elTectingt-hiscompression is derived for [which would be otherwise wasted is saved.

The supply of cold air having been introduced and compressed, theengine-is prepared to be impelled by the expansive force of the heatedair. The eduction-valve 9 having remained closed during the greater.part of the inward motion of the working-piston, the inductionair fromthe heater to the cylinder, by which the working-piston. .The form ofthe face of the cam Z, as represented, is such as to cause the piston tobe carried back with a rapid accelerated motion until it comes nearly'iucontact with the working-piston; and at first in this outward motion ofthe supply-piston the already-compressed supply-air between the twopistons is still further compressed, not by the power of the engine, butby the elastic force of the heated air, the supply-piston beair from theheater on one side and the cold air on the other, with the self-actingvalve 1' (in the side of the cylinder) interposed be? tween the two, forit must be remembered that as the heater and regenerator are incommunication the air, which is a perfectly elastic fluid, will be underequal pressure in both, notwithstanding a portion is more highly heatedthan'the other, and as the supply-air in the'cylinder is simplyseparated from the air in the regenerator by the interposed valve r inthe side of the cylinder the supply-piston will be'moved outward by theheated air until the supply-air is compressed to an equal tension, andthen the further motion of the supply-piston, efl'eeted by the cam l' asita preaches the working-piston,will transfer the supply-air from thecylinder to the regenerator through the valve r. The only power expendedby the engine in this transfer will be the small amount required to movethe suppl ypiston between two equal pressures to give the slightpreponderance to open the valve 7', through which the transfer is made.The moment the supply-piston passes this'valve and overtakes the workingpiston the preponderance of pressure ceases and the valve closes bygravity. If desired, however, a positive mot-ion properly regulated maybe imparted to this valve byasuitable valve-gear. The operations j ustdescribed for the final compression and transfer of the supply-air takeplace during the time that the working-piston is at rest, or nearly so.It is while the crank is passing the dead-point farthest from the arm q,connected by the rodr withthe crank, and as the crank and theconnect-ingrod have their centers of motion at the time of passing thedead-point on the same side of their points of connection, it followsthat during the time the crank moves a given distance each side of thedead-point the piston will move through a distance comparatively muchshorter-than when the crank moves the point, for in the one case thecrank and the valvehis now opened,which admits the heated thesupply-piston is forced outward toward' ing, as it were, suspendedbetween theheated to the one necessary same distance each side oftheopposite dead-,

connecting-rod simplyrepresent the radii of two eccentric circles, whilein the other they represent the radii of two opposite circles. By

pelled outward by the expansive force of the heated air and thesupply-piston by the catnnoie'ment described.

. The form of the catnl', which acts on the roller j to gover'n theoutward stroke of the supply-piston, must be such, as represented, thatthe piston will move with a rapidly-aocelerated motion until itapproaches the work ing-pistointhen gradually retarded, and from thepoint 1 to 2 its curvature must be such that its motion will be inunison with the motion 'Ii'mparted to the working-piston, by'reason ofits connection with the crank, modified by the interposition of thearms. 0 and q, operating on the principle of the bent lever.

It has been shown that the alternating leverage ot' the arms 0 of thetwoengines is such as to apply the power for compressing the supply-air tothe best advantage, and it remains to show the connection between thetwo in furtherance of t his'e'conomy. It will be seen that the arm 01',connected with the working-piston fllfllng th' outward stroke, graduallyincreases in letterage asthe heated air, by dilatation, .gradullydecreases in tension. Now the-leye'i'agept' this arm gradually increasesdn ring the outward stroke of the working-piston of one: engi heas itgradually decreases in the other' engine', where the Working-piston iscompressing thesupply-air', and vice versa.

Iniias'been stated that the power exerted on the workingpiston tocompress the supply-air was not an actual consumption, but a meretran'stjerofipewer. This will beapparent from the description. of theentire operation, be cause the air thus compressed is transferred to theregenerator and from the regenerator to the heater, andthence to thecylinder, where it exerts on the piston the elastic force firstimpressed upon it by the piston, together with the tensive force whichit has acquired by being heated, so that the compression which itreceived at first from the piston when working in one direction itreturns to the piston when working in the'opposite direction under theadvantages due to the arrangement of the two engines, as abovespecified.

By the alternate strokes of each engine the required supply of cold airis introduced, compressed, and transferred from the cylinder to theregenerator, carried through the regenerator, thence through the heater,and from the heater back to the cylinder, and in this circuit it is,grad nall-y heated, first by the heat which it takes up from theescaping heated air, and then by the heat of the furnace, and asatmospheric air is a bad conductor of ca- 1or ic,the heat will not becarried back by condnction from the heater to the regenerator, but afterthe heated air has exerted its elastic force in the cylinder in escapingit transfers its surplus heat to the supply-air on its passage throughthe rcgcnerator. The object of the regenerator being, however, merelythat of economizing fuel, it is evident that the supply-air may bepassed directly from the cold end of the working-cylinder, by the actionof the supply-piston, to a heater communicating with the other end ofthe working-cylinder.

What I claim as my invention, and desire to secure by Letters Patent,is-

1. The method of supplying fresh air to the engine, compressing andtransferring it to the regenerator and'heater,'or either, by the actionof the supply and working pistons within the one cylinder, operating onthe principle and in the manner substantially as herein de--seribed,whereby the air is admitted under at- 'mospheric pressure as thesupply-piston is moving from the workingpiston as the previous charge ofheated air is exhausting, so that-the said supply-piston moves inequilibr'ia, or nearly so, and bywhich, also, the sup ply-air is finallycompressed and then transferred the regenerator and heater, oreither,;as

the snpply-piston moves between the supplyair and heated air during theperiod of the nearly stationary position-of the working-piston. I

2. In combination with the double-piston movement of each cylinder, themethod ot'connecting the workingpistons oftwo single-acting engines toconstitute a double-acting engine by means of two sets of vibrating armsattached to each other and vibrating on a common center connected withthe two workingpistons, and with the two cranks on opposite sides of theaxis of the crank-shalt, the two sets of arms operating on the principleof the bent lever, and the crank-shaft being so located relatively tothe cylinders and the centers of vibration of the arms, substantially asdescribed, that the Working-piston shall be at the end of its inwardstroke at the time the crank is passing the dead-point farthest from thepoint of connection of the connectingrod with the vibrating arm, asdescribed, by which the power of that working-piston which is beingimpelled by the heated air is applied to the best advantage to operatethe other working-piston during its return-stroke, and by which,also,the working-piston reinainsnearly at, rest during the time thesupplypiston is making that part of its outward stroke during which thepartially-compressed air is finally and fully compressed and transferredto the regenerator and heater, or either, as described.

Witnesses:

WM. H. BISHOP, ANDREW 'DE LACY.

ERIGSSON.

